Polyurea-thickened grease composition

Abstract

A grease composition comprising a major amount of an oil of lubricating viscosity; a thickener selected from the group consisting of monoureas, diureas, triureas and polyureas, or mixtures thereof; and an oil soluble neutral or overbased zinc salt of a carboxylic acid selected from the group consisting of zinc salts of fatty acids, the zinc salts of hydrocarbyl-substituted salicylic acids, and zinc glyoxylates is disclosed.

What is claimed is:  
     
       1. A grease composition comprising a major amount of an oil of lubricating viscosity and an additive further comprising (A) a thickener selected from the group of monoureas, diureas, triureas, and polyureas, and mixtures thereof, and (B) an oil-soluble neutral or overbased zinc salt of a carboxylic acid selected from the group consisting of zinc salts of fatty acids, the zinc salts of hydrocarbyl-substituted salicylic acids, and zinc glyoxylates, provided that if (B) is the zinc salt of a fatty acid, the fatty acid is not ricinoleic acid and wherein the grease compositions does not contain boron nitride powders. 
     
     
       2. A grease composition according to claim  1  wherein the oil-soluble zinc salt comprises an overbased zinc salt. 
     
     
       3. A grease composition according to claim  1  wherein the oil-soluble zinc salt comprises a zinc salt of a hydrocarbyl-substituted salicylic acid corresponding to the following formula:                    
       wherein R is a hydrocarbyl group. 
     
     
       4. A grease composition according to claim  3  wherein the oil-soluble zinc salt comprises an overbased zinc salt of a hydrocarbyl-substituted salicylic acid. 
     
     
       5. A grease composition according to claim  3  wherein the R group contains between about 7 and about 40 carbon atoms. 
     
     
       6. A grease composition according to claim  3  wherein the R group contains between about 7 and about 24 carbon atoms. 
     
     
       7. A grease composition according to claim  3  wherein the R group contains between about 12 and about 18 carbon atoms. 
     
     
       8. A grease composition according to claim  1  wherein the oil soluble zinc salt comprises a zinc salt of a fatty acid. 
     
     
       9. A grease composition according to claim  8  wherein the oil soluble zinc salt is selected from group consisting of the zinc salts of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid. 
     
     
       10. A grease composition according to claim  8  wherein the oil soluble zinc salt is the zinc salt of oleic acid. 
     
     
       11. A grease composition according to claim  10  wherein the oil soluble zinc salt is an overbased zinc salt of oleic acid. 
     
     
       12. A grease composition according to claim  1  wherein the oil soluble zinc salt comprises a zinc glyoxylate of the following formula:                    
       wherein Ar is an aromatic group containing 1 to 3 aromatic rings, R is one or more hydrocarbyl groups containing from about 4 to about 150 carbon atoms provided that the number of R groups shall not exceed the available valences on the aromatic group. 
     
     
       13. A grease composition according to claim  12  wherein R contains about 4 to about 100 carbon atoms. 
     
     
       14. A grease composition according to claim  12  wherein R contains about 4 to about 50 carbon atoms. 
     
     
       15. A grease composition according to claim  12  wherein R contains about 4 to about 24 carbon atoms. 
     
     
       16. A grease composition according to claim  12  wherein R contains about 7 to about 100 carbon atoms. 
     
     
       17. A grease composition according to claim  12  wherein R contains about 7 to about 50 carbon atoms. 
     
     
       18. A grease composition according to claim  12  wherein R contains about 7 to about 24 carbon atoms. 
     
     
       19. A grease composition according to claim  12  wherein R contains about 12 to about 18 carbons atoms. 
     
     
       20. A grease composition according to claim  1  wherein the thickener comprises a monourea. 
     
     
       21. A grease composition according to claim  1  wherein the thickener comprises a diurea. 
     
     
       22. A grease composition according to claim  1  wherein the thickener comprises a triurea. 
     
     
       23. A grease composition according to claim  1  wherein the thickener comprises a polyurea. 
     
     
       24. A method of lubricating metal surfaces that move with respect to each other that comprises placing between said metal surfaces an appropriate quanitity of a grease composition comprising of a major amount of an oil of lubricating viscosity, a thickener selected from the group consisting of monoureas, diureas, triureas and polyureas, or mixtures thereof, and an oil-soluble neutral or overbased zinc salt of a carboxylic acid selected from the group consisting of zinc salts of fatty acids, the zinc salts of hydrocarbyl-substituted salicylic acids, and zinc glyoxylates.